1. Field
One embodiment of the invention relates to a printed-wiring board incorporating a chip product included in electronic circuits, a manufacturing method of the printed-wiring board with a built-in component, and an electronic device using the printed-wiring board with a built-in component.
2. Description of the Related Art
Conventionally, as for component mounting techniques directed to printed-wiring boards, various techniques have been proposed which address negative effects of voids formed at the time of mounting components. For example, Japanese Patent Application Publication (KOKAI) No. H08-274211 discloses a technique which addresses formation of voids at the time of mounting BGA (ball grid array) components. This technique concentrates voids in a specific area, thereby preventing solder cracks caused by temperature cycling.
On the other hand, in recent years, as for a printed-wiring board forming a plurality of layers used in an electronic circuit device, a substrate manufacturing technique has been developed toward practical use. In this substrate manufacturing technique, a printed-wiring board with a built-in electronic component is manufactured by: solder bonding chip components, such as passive components, on a conductor pattern (pad) formed on an inner-layer side pattern-forming surface; and stacking an insulating material on the inner-layer side so as to cover the chip components with the insulating material. In the printed-wiring board with a built-in component having such a structure, voids (air pockets or gas pockets) are formed in the gap between the chip components and a surface on which the conductor pattern bonded to the chip components. If the voids formed in the gap are heated in various heating processes at the time of manufacturing substrates including, e.g., a subsequent stacking process and a component mounting (reflowing) process, or heated in, e.g., heat reception after the printed-wiring board is incorporated in an electronic device, various problems may occur due to thermal expansion of the voids, such as detachment of the conductor pattern, damage to the chip components, break in a circuit, degradation of rigidity of the board, etc.